1. Field of the Invention
The present invention relates to gas delivery systems for supplying a gas required for manufacturing semiconductor devices. More specifically, the present invention relates to a gas delivery system having a non-shutdown function for preventing an unwanted shutdown.
2. Description of the Related Art
Manufacturing equipment, such as equipment to manufacture semiconductor devices, use various types of fluids such as gases. For example, semiconductor manufacturing equipment requires a gas delivery system for supplying a gas during a production of semiconductor devices. The reliability of a gas delivery system, such as a cylinder cabinet, is known to have a direct influence on the rate of operation of semiconductor manufacturing equipment which in turn affects overall productivity. Accordingly, it is very important to reliably operate the gas delivery system. Thus, various methods for reliably delivering a gas from a gas supply source to manufacturing equipment have been proposed.
In general, gas delivery systems or gas supplying apparatuses are categorized into different types, i.e., single delivery systems or auto delivery systems, according to the properties of the supplied gases. However, in recent years, the auto delivery systems, which enable automated gas supply, have been widely used in order to increase the rate of operation of semiconductor manufacturing equipment and improve overall productivity.
FIG. 1 is a schematic diagram illustrating a conventional gas delivery system. FIG. 2 is a schematic diagram illustrating an emergency shutdown of the conventional gas delivery system. Referring to FIGS. 1 and 2, a typical gas delivery system may comprise a main controller 10 and a gas supplier 20 (or a panel and pipeline unit).
The main controller 10 may include a programmable logic controller (PLC), in which a software program for controlling the gas supplier 20 is installed and operated. The main controller 10 controls the flow of gas from the gas supplier 20 to manufacturing equipment 30 where the manufacture of semiconductor devices are conducted.
Specifically, as shown in FIG. 2, the main controller 10 may include (a) a central processing unit (CPU) for performing operations of controlling gas supply, (b) a power supply for supplying power to the CPU, and (c) parts for transmitting and receiving signals, such as an analog signal unit, a digital signal input (D/I), and a digital signal output (D/O). The CPU controls the operations of the gas supplier 20 based on a predetermined operating program.
The operating status of the main controller 10 is displayed on a display unit 50, which is coupled to the CPU via RS232. Because the display unit 50 is a touch-screen type display, a worker can input a new command to the CPU of the main controller 10 using the display unit 50.
The main controller 10 controls various gas delivery paths installed in the gas supplier 20 so as to deliver a required gas to manufacturing equipment 30. For this, the main controller 10 controls operations of opening/closing off a plurality of valves included in the gas supplier 10. Here, the valves are air valves, which are remotely controlled by the main controller 10.
The gas supplier 20 comprises a plurality of gas containers (e.g., container A and container B of FIG. 1); on/off valves such as air valves (AV of FIG. 1) for distributing, turning on/off, and delivering a gas from the gas containers to the manufacturing equipment 30; pressure transducers (PT of FIG. 1); pressure regulators (REG of FIG. 1); and filters (LF of FIG. 1), which are coupled in a spool apparatus. Using selected parts of the gas supplier 20, the main controller 10 can determine gas pressure and the on/off status of the valves.
Referring to FIG. 1, each of the part included in the gas supplier 20 is driven by a program signal, which is set in the CPU of the main controller 10. For example, a gas contained in the container B is delivered along a gas delivery path to the manufacturing equipment 30. Initially, a valve 21 of the container B opens, pressure is primarily checked at PT1B 22, a gas is primarily filtered at LF1B 23, a first valve AV2B 24 opens, pressure is secondarily checked at PT3B 25, a second valve AV3B 26 opens, and a gas is secondarily filtered at LF2 27. The pipeline includes ¼″ and ½″ lines which are coupled to an end of the manufacturing equipment 30.
If gas leakage is detected along the gas delivery path or in the gas supplier 20, a gas leakage detector 40 generates a gas leakage signal. The gas leakage signal is transmitted through an interface box 45 to the main controller 10. Next, the main controller 10 transmits output signals for turning on a warning lamp 55, closing off all the valves of the gas supplier 20, and displaying an emergency shutdown state on the display unit 50. Such emergency shutdown results from a normal interlock function.
However, it is frequently reported that the emergency shutdown occurs merely in response to a malfunction of the main controller 10, not an emergency situation such as a gas leakage or the like. That is, when the CPU of the main controller 10 is incapacitated due to various internal/external factors, all the valves of the gas supplier 20 are shut down. In particular, both the first valve AV2B 24 and the second valve AV3B 26 of FIG. 1 are shut down, which leads to an immediate interruption of the gas supply to the manufacturing equipment 30.
In other words, when any malfunction or error is detected in the CPU of the main controller 10, the gas supply is immediately interrupted, and the manufacturing equipment 30 undergoes an emergency shutdown. As a result, the rate of operation of the manufacturing equipment 30 is sharply reduced.
However, when a non-urgent error or interruption in the flow of gas which does not constitute an emergency, such as a gas leakage, is detected in the main controller 10, it is preferable to keep supplying a gas to the manufacturing equipment 30 considering the consequences which result from a substantial decrease in the rate of operation of the manufacturing equipment 30.